CVE-2019-6809 in Modicon M580
Summary
by MITRE
A CWE-248: Uncaught Exception vulnerability exists in Modicon M580 (firmware versions prior to V2.90), Modicon M340 (firmware versions prior to V3.10), Modicon Premium (all versions), Modicon Quantum (all versions), which could cause a possible denial of service when reading invalid data from the controller.
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Analysis
by VulDB Data Team • 08/28/2020
The vulnerability described in CVE-2019-6809 represents a critical uncaught exception flaw affecting several Modicon series programmable logic controllers from Schneider Electric. This weakness manifests as a CWE-248 classification, indicating that the affected devices fail to properly handle exceptional conditions during data reading operations. The impacted controllers include the Modicon M580 with firmware versions prior to V2.90, Modicon M340 with firmware versions prior to V3.10, as well as all versions of Modicon Premium and Quantum series controllers. The flaw specifically occurs when these industrial control systems attempt to read invalid data from their internal controllers, leading to potential system instability and operational disruption.
The technical implementation of this vulnerability stems from inadequate error handling mechanisms within the firmware of these industrial controllers. When legitimate or malicious actors attempt to access non-existent or corrupted data structures within the controller's memory space, the system fails to gracefully manage the exception and instead experiences a complete system crash or hang. This behavior creates a denial of service condition that can persist until manual intervention occurs through system reboot or power cycling. The vulnerability is particularly concerning because industrial control systems operate in environments where continuous operation is critical, and any disruption can lead to production halts, safety system failures, or cascading operational issues.
From an operational perspective, the impact of this vulnerability extends beyond simple service interruption to potentially compromise industrial safety and process control systems. The Modicon series controllers are commonly deployed in critical infrastructure environments including manufacturing plants, oil and gas facilities, water treatment systems, and other industrial automation settings where system reliability is paramount. When these controllers experience unhandled exceptions leading to denial of service, production lines may halt unexpectedly, safety systems could fail to respond appropriately, and process control may be lost entirely. The vulnerability's exploitation could occur through network-based attacks or physical access to the devices, making it a significant concern for industrial cybersecurity programs.
The mitigation strategies for this vulnerability primarily involve firmware updates from Schneider Electric, specifically targeting the affected firmware versions mentioned in the CVE description. Organizations should immediately assess their deployed Modicon controllers to identify systems running vulnerable firmware versions and implement the appropriate patches or upgrades. Additionally, network segmentation and access controls should be enforced to limit physical and network access to these critical control systems. Monitoring should be implemented to detect unusual system behavior or repeated access attempts that might indicate exploitation attempts. According to ATT&CK framework, this vulnerability aligns with techniques involving system compromise and denial of service operations, making it a critical target for industrial cybersecurity defenses. Organizations should also consider implementing intrusion detection systems specifically tuned to monitor for abnormal controller behavior patterns that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining current firmware versions and establishing robust patch management processes for industrial control systems, as outlined in various cybersecurity frameworks including NIST SP 800-80 and IEC 62443 standards for industrial automation and control systems security.